The invention pertains to dust collection and recovery devices. Particularly, the invention pertains to safety devices for removing and collecting vehicle friction brake and clutch dust while the same are exposed to a worker's environment.
The removal of contaminated dust from the workplace environment has long been a concern to workers, management and health care professionals. This concern has become increasingly more intense with the realization that certain forms of common workplace contaminants, notably asbestos, pose significant health risks. These risks are known to include asbestosis, mesothelioma and cancer. Therefore, from a safety standpoint it is imperative that hazardous dust, especially asbestos-containing dust, be efficiently and effectively removed from a worker's environment.
Vehicle friction brake and clutch assemblies are well known sources of hazardous dust. These assemblies typically contain contact surfaces, i.e., brake shoes or clutch pads, which generally consist of a compound of materials, including asbestos. Over time, the brake and clutch facings wear down through use and create dusty residues of the facing material. This asbestos-containing residue accumulates within the brake drum and the clutch bellhousing, and on or about the brake shoe and backing plate assembly.
The accumulated dust becomes troublesome when work is required to be done on a vehicle's brakes or clutch. When working, for example, on an automobile's brakes, the brake drum must be removed from the backing plate before the brakes can be inspected or replaced. However, during removal of the drum from the backing plate, asbestos-containing dust is released into the work area. Additionally, after removal of the drum, residual, asbestos-containing dust will remain on the brake shoes and backing plate.
Similarly, during clutch inspection or replacement, removal of the transmission from the bell housing exposes the interior clutch assembly to the worker's environment. During exposure of the interior clutch assembly, asbestos-containing dust will likewise be released into the worker's environment and residual dust will remain on the interior surfaces of the clutch assembly.
In each instance, i.e., whether working on a vehicle's brakes or clutch, asbestos-containing dust must be safely removed from the worker's environment in a manner which will protect the worker, other persons in the area, and the surrounding environment from contact with the toxic substance, asbestos.
In years past, the fastest and most common method of removing vehicle brake and clutch dust was to simply blow the dust off of the brake and clutch surfaces using a high pressure jet of air from, e.g., a shop air-hose. However, this action typically created a dark cloud of entrained dust which would contaminate the air for long periods of time. Workers inhaled and ingested this contamination and would often continue to expectorate the dust for hours following contact with it. Additionally, microscopic asbestos fibers are known to remain airborne for extended periods, up to 2 days and longer, creating a health hazard long after visible dust has settled.
Previous attempts to eliminate the unpleasant clouds of brake dust included surrounding the brake assembly with a hood and removing the dust through the combined application of high pressure air upon the brake assembly concurrently with the evacuation of the hood by use of a vacuum pump. Some devices even utilized filtration to one degree or another. The filtration problem, however, is complicated by the fact that the hazardous asbestos fibers are extremely small, often being less than one micron in size. Many prior brake dust recovery devices eliminated some macroscopic sized particles of dust but had no effect on microscopic particles, notably asbestos, which, as previously stated, are known to cause disease and cancer in man. These prior systems dealt with filtration of the particulate in only a cursory manner and failed to address the need to remove submicron sized particles from the air and from the surfaces of the housing. Indeed, many of these prior systems were concerned only with the removal of visible particles, e.g., dust clouds.
Prior art dust collection devices also generally lacked provision for the safe handling and disposal of the particulate after collection in the device. Particularly, typical prior art dust collection devices failed to provide safe and effective means for changing disposable filter bags. Prior art systems required the collection device to be fully open before the disposable filter could be removed, thereby exposing the worker to concentrated amounts of the very contaminant sought to be eliminated.
Previously disclosed brake dust removal and collection devices have proven to be inadequate from a practical standpoint as well. The prior systems were awkward and cumbersome to handle and generally comprised a plurality of components which needed to be individually moved to a work site and connected prior to commencement of work.
Further, all known prior brake dust removal and collection systems require the removal of the brake drum prior to positioning the device about the backing plate and shoe assembly. During this time, i.e., while the brake drum is being removed prior to positioning the device, asbestos dust is being spilled onto the floor and dissipated into the worker's environment.
Further still, many of the hood-type enclosures used in prior brake dust removal and collection apparatuses were manufactured using mostly opaque material which restricts light to the brake assembly and consequently reduces worker visibility during the cleaning operation.
Size has also presented a drawback to the effective use of devices in the field of this invention. Most prior brake dust collection and removal devices were designed only for use with automotive sized brake assemblies. One manufacturer, Nilfisk, is known to offer a larger size dust removal and collection device for use with heavy truck brake drums. However, this manufacturer also recommends the purchase of an automobile size unit for smaller automobile brake assemblies. Therefore, the purchase of two of the previously known devices is ordinarily required to cover the full range of work typically present in vehicle shops.
Some of the prior brake dust removal devices provide an aperture in the hood of the device to allow an operator to insert his hand into the enclosure. The aperture is typically covered by a flexible diaphragm which is slit in a pie fashion to enable the operator to insert his hand and arm into the unit. A cotton sleeve is known to have been provided in one prior device to protect a worker's upper arm. However, no provision has previously been made to protect the worker's hand and arm from contacting the asbestos dust.
As previously mentioned, asbestos dust also presents a problem for workers handling vehicle friction clutch assemblies. There are no known devices or attachments to existing known brake dust removal and collection devices which are useful in removing and collecting asbestos dust from clutch assemblies.
There have been several United States Patents granted previously which are generally directed to cleaning systems for brake housings. These include U.S. Pat. Nos. 3,222,707 (Allenbaugh, 1965), 3,510,905 (Bannert, 1970), 3,731,340 (Pitre, 1973), 3,972,089 (Parks, 1976), 3,978,547 (Lawson, 1976) and 4,205,412 (Weber, 1980). It is believed that these apparatus have not gained any significant commercial acceptance.
One previous brake dust removal and collection device which is known to be commercially available is that sold by Nilfisk, Inc. under the trademark Asbestos-Clene. The Asbestos-Clene device comprises separate vacuum and containment units connected by a flexible hose. The device incorporates a high efficiency particulate air (HEPA) filter into the vacuum system. The Nilfisk system, however, has many of the limitations of the prior art which have been noted above. These limitations include the following: (1) The brake dust removal and collection device is size constrained. The device is available in automotive and truck sizes. The automotive size unit will not accommodate truck brake assemblies. The truck size unit may accomodate some automobiles, however, it is believed that its large size would result in little actual use of the device. Therefore, a busy automotive shop would be required to purchase separate units for trucks and automobiles. (2) The unit, being cylindrically constructed of steel or dark plastic, is opaque with the exception of a small window which allows only a limited amount of light to pass into the work area. Visibility inside the cylindrical unit is poor and during operation, when the drum is filled with a cloud of black dust, visibility through the window is extremely poor. (3) The access portal for the operator's hand is provided with a slit diaphragm of cloth sleeve which is intended to form around the operator's arm leaving it and the operator's hand exposed to asbestos dust. (4) The Asbestos-Clene containment unit is separate from the vacuum and requires a mechanic to handle and connect the two pieces of equipment. (5) The vacuum component to the system utilizes a "shakedown" bag for containment of the asbestos. This may raise the question of safety during the "shakedown" and subsequent filter changes. (6) The large truck size unit has two unprotected hand apertures for worker access to the brakes, but the apertures are 180.degree. apart making simultaneous use thereof by one worker impracticable.
An essential attribute of any worker safety device is that it actually be used in its intended manner and for its intended purpose. However, a safety device which is difficult to work with will probably fail to be used in its intended manner and for its intended purpose by the worker who may forego use of the safety device to save time and for convenience.
It is therefore an object of the invention to provide a brake dust removing and collecting device which will remove hazardous materials from the workplace and thereby improve the quality of a worker's environment.
It is a further object of the invention to provide a brake dust removing and collecting device which does not require removal of the brake drum prior to surrounding the brake.
It is a further object of the invention to provide a brake dust removing and collection device which may also be used to remove and collect hazardous dust from friction clutch assemblies.
It is a still further object of the invention to provide a hazardous dust removing and collection device which is convenient for a worker to use and effective and will hence be more likely to be used than were the devices of the prior art.
It is a still further object of the invention to provide a hazardous dust vacuum and filter assembly which is safe, effective and efficient.
It is yet another object of the invention to provide a brake dust removal and collection device which is highly portable and suitable for any size brake or clutch.